The invention relates to liquid drug transfer devices for secure telescopic snap fit on injection vials.
ISO 8362-1 Injection containers and accessories—Part 1: injection vials made of glass tubing standardizes vial sizes, vial dimensions and vial tolerances. ISO 8362-1 defines the following terms: Vial tube, vial crown and vial neck intermediate a vial tube and a vial crown. The vial tube has a closed end and an Outer Diameter (OD) d1. The vial crown has a crown opening and an Outer Diameter (OD) d2. The vial neck has an Outer Diameter (OD) d3 and an Inner Diameter (ID) d4. The vial crown has an uppermost vial crown rim encircling the crown opening and a lowermost vial crown rim towards the vial neck. The crown opening has the same inner diameter as the vial neck. The injection vial has a vial shoulder between the vial neck and the vial tube. The vial tube and the vial shoulder meet at an uppermost vial tube rim. The diameters have the relationship: d1>d2>d3>d4. Most vial crown outer diameters are available in several vial tube outer diameters, for example, a vial crown outer diameter d2=20 mm is available in three standard vial tube outer diameters d1=22 or 24 or 30 mm. Accordingly, injection vials are referred to by their vial crown outer diameters and not their vial tube outer diameters.
Liquid drug transfer devices include a vial adapter having a transverse vial adapter top wall, a hollow puncturing cannula for puncturing a vial stopper and a downward depending skirt. The downward depending skirt extends sufficiently downward to shield a puncturing cannula tip to prevent inadvertent user contact therewith. The downward depending skirt is shaped and dimensioned to snugly telescopically snap fit onto a particular vial crown outer diameter. Accordingly, vial adapters in a similar manner to injection vials are referred to in terms of a vial crown outer diameter for which they are intended to telescopic snap fit thereon. To ensure a vial adapter can be telescopically snap fit onto all the standard vial tube outer diameters of a particular vial crown outer diameter, its downward depending skirt is dimensioned to terminate above a vial shoulder. However, such downward depending skirts do not assist a user to align a vial adapter co-axial with an injection vial leading to common misalignment. Misalignment of a vial adapter with respect to an injection vial typically leads to the formation of a tear in a vial stopper as discussed in inter alia commonly owned U.S. Pat. No. 8,608,723 to Lev et al. entitled Fluid Transfer Devices with Sealing Arrangement.
Commonly owned U.S. Pat. No. 8,070,739 to Zinger et al. entitled Liquid Drug Transfer Devices for Failsafe Correct Snap Fitting onto Medicinal Vials discloses liquid drug transfer devices having a vial adapter designed to assist a user to align a vial adapter with an injection vial. The liquid drug transfer devices include a vial adapter having a downward depending skirt with at least two non-adjacent vial retention flex members for snap fitting over a vial crown for vial retention purposes and at least two non-adjacent vial guidance flex members longer than their counterpart vial retention flex members for guiding a vial adapter with respect to an injection vial prior to snap fitting the vial adapter thereon.
During the snap fit on an injection vial, the vial guidance flex members typically abut a vial shoulder and slide radial outwards on being outwardly radially flexed with respect to their vial adapter centerline at their junctures with their vial adapter top wall. The outward radial sliding of vial guidance flex members is dependent on the slope of a vial shoulder with a steeper slope facilitating outward radial sliding. The outward radial flexing of the vial guidance flex members at the junctures with their vial adapter top wall leads to a detachment reaction force opposing a manual attachment force for telescopic snap fitting a vial adapter on an injection vial. The greater the diameter of an injection tube the greater a detachment reaction force which at best leads to weakening a telescopic snap fit and at worst can lead to detachment.
Moreover, the telescopic snap fit of a vial adapter on an injection vial is not uniform for all the vial tube outer diameters for a particular vial crown outer diameter because the vial guidance flex members are outwardly radially flexed differently for different vial tube outer diameters. Also, larger vial tube outer diameters cause a vial adapter telescopic snap fitted onto an injection vial to present an awkward gripping surface for a user holding the vial adapter, for example, for attaching and detaching a syringe.
There is therefore a need to provide liquid drug transfer devices with vial adapters for providing a secure telescopic snap fit on a vial crown for all standard vial tube outer diameters for a particular vial crown outer diameter.